Question

Which of following statements is correct for physisorption?

• A. It involves formation of covalent or ionic bonds.
• B. It is favoured at high temperature.
• C. It is reversible.
• D. It is very specific.

Hint:

Think of physisorption like dust settling on a table—easily removed (reversible), happens anywhere (not specific), and no chemical bonds are formed.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
We need to identify the correct characteristic of physical adsorption (physisorption) from the given options.

Step 2: Key Formula or Approach:
Physisorption occurs due to weak van der Waals forces between the adsorbate gas and the adsorbent surface. Chemisorption, on the other hand, involves strong chemical bond formation.

Step 3: Detailed Explanation:
Let's evaluate each option based on the properties of adsorption:
(A) Incorrect. Physisorption involves weak van der Waals forces, not chemical (covalent or ionic) bonds. Bond formation describes chemisorption.
(B) Incorrect. Physisorption is an exothermic process and is favored at low temperatures. High temperatures provide enough thermal energy to overcome the weak van der Waals forces, causing the gas to desorb.
(C) Correct. Because the forces holding the molecules to the surface are weak, the process is highly reversible. Lowering the pressure or increasing the temperature easily removes the adsorbed gas.
(D) Incorrect. Physisorption is not specific; any gas will adsorb on any solid surface to some extent, depending primarily on how easily the gas can be liquefied.

Step 4: Final Answer:
The correct statement is that physisorption is reversible, matching option (C).